Nuclear Waste Tamed by Bacteria

Mother Nature possesses countless ways to keep the cycle of life — the phases of birth, life, death, and reuse — in continuous motion. One example of this is the bacteria and microbes found in soil, which, along with other elements in the natural world, help to break down flora and fauna that have reached the ends of their lives, and are ready to be disassembled into their constituent parts, to then be recycled by those members just above them on the great food web.

The microbe's ability to take in substances of all types, and convert them into less toxic forms, is often referred to as "bioremediation". Perhaps the best-known use occurred during the 1980s, when certain types of microbes were used to clean up toxic organic materials — primarily fuel and solvent spills. In essence, the hungry bacteria ate the fuels, by breaking down the long-chain hydrocarbons, and "breathed" in the solvents, turning them into nontoxic forms.

Now that power for natural detoxification is being directed towards the nuclear contaminants produced by numerous American energy companies, mining companies, and military weapons programs. Throughout the United States, there are dozens of federal laboratories that are facing the daunting task of somehow neutralizing all of this toxic waste. If current research yields results, then they may get a tremendous amount of help from the lowly bacterium. Civil and environmental engineering researchers at Stanford University and the Oak Ridge National Laboratory (ORNL) are focusing on the toxic uranium often detected in groundwater found near uranium mines or uranium enrichment sites — groundwater that can easily contaminate surface water, which then threatens all organisms that depend upon that surface water.

In the past, the contaminated soil would be excavated, and the contaminated water would be pumped out and treated artificially. But these approaches invariably caused other disposal problems, and were also quite expensive. As an alternative, the researchers have found subsurface microorganisms, already naturally occurring in the soil, which are capable of converting the dissolved uranium into a more solid form that is far less likely to be spread by water. So far, this approach has proven most effective against the more highly contaminated sites. Yet the results can be startling. For instance, the researchers were able to process groundwater containing more than 1000 times the regulated limit for uranium for potable water, and, utilizing those microorganisms, effectively reduce the uranium levels down to the drinking water limit.

At this point, the processed uranium waste is solid enough not to flow like a liquid; but the process is hoped to be taken even further, whereby the end result will be a full solid, which can be handled and disposed of even more easily. It will be a case of powerful bacteria and microbes exchanging their usual role of breaking down solids to be taken up again by plants, and instead creating solids from contaminated water output by nuclear power plants.